After placing tabs on a 2d contour toolpath, if you click on the "x" to remove the tabs, the display continues to show the tabs, but the handle goes away. You have to add a new tab or change to "By distance" under the Tab Positioning pull down to refresh the display.
I would love to have tab locations that have been placed via the "By Distance" pull down remain placed when switching to "At points". This would allow you to move the tabs that are holding adjacent parts (but not aligned) as well as give a head start on large parts that have both long straight sections and complex detailed sections.